Mathematics - 2013-02-08 (page 3 of 3)

robjohn

17:00

@JacobBlack I'm glad that you can see $\displaystyle\left(\frac12\right)$ properly again.

user19161

@robjohn Haha, yes. I see you have discovered my secret identity...

Orange Harvester

@JacobBlack I was the 10th one who starred.

robjohn

@JacobBlack I just replied to your previous message.

user19161

@OrangeHarvester OMG, it has 11 stars now...

Charlie

When you wish upon a star...

user58512

17:03

@robjohn, do you know how to find the continued fraction of sin?someoen asked it on the site and it's not the ratio of two power series so I couldn't use the same technique

@robjohn, I mean it follows from Gauss' hypergeometric but thats difficult stuff..

robjohn

@user58512 I'd try to look at $\sin(x)=\frac{\sin(2x)}{2\cos(x)}$ and see if we get something similar to $\tan(x)$

user58512

oh that is a good idea!

I'll try it, if it works ill post answer & link your message

user17753

17:32

Hey guys, is it correct to write $n,k \in \Bbb N$ meaning both n and k are variables that belong to the set of natural numbers. Or does it have to be written out as $n \in \Bbb N, k \in \Bbb N$?

user58512

its' fine

user58512

18:00

I don't seem to be getting the right answer for sin continued fraction

I get terms like [2^6 + 7(2^4 * 6 - 1)]/7!

getting these continued fractions must be an art

Ed Gorcenski

19:12

morning

user58512

hi

Orange Harvester

@JonasTeuwen another cool thing

user19161

The unregistered user posting factorisation questions one after another is making me upset...

Ed Gorcenski

Yes

In general, people who don't stop and think make me upset.

user19161

Of course, I am not truly upset, just exaggerating a little. I have too many problems to be concerned over a random stranger on the internet LOL

user19161

19:25

Also, this is the kind of question where you don't even know how to post an answer to LOL

user58512

there's a lot of questions on this site I don't know how to answer

user19161

Of course, that applies to everyone.

user19161

@EdGorcenski OK asker is 12, so understandable.

Ed Gorcenski

I could tell by his typing.

Anyhow, I badly need coffee. BRB

user58512

I want coffee

N3buchadnezzar

19:40

Anyone familiar with matlab?

I am trying to plot $f(r,\theta)=\cos(2\theta)/r^2$

user58512

hi @anon

anon

hey

user58512

I'm finding my math class very hard, do you have any advice ?

anon

not in full generality...

user19161

@user58512 Yes, keep reading and thinking and writing.

Sgernesto

19:50

hello

user58512

hi

Sgernesto

what kind of math class?

what do you learn there?

user58512

its about number theory

Sgernesto

i see

elementary nuber theory?

user58512

analytic

Sgernesto

19:54

oh

there a book by apostol

user58512

yea, I tried to read it a few years ago

some things I learned from it have helped me in this

Sgernesto

i only took a course of elementary number theory

user58512

so did I, did you learn quadratic reciprocity?

Sgernesto

good luck

user58512

thanks

Sgernesto

19:56

well yes

legendre symbols and all that

user58512

cool

Sgernesto

but i don't know well the subject

user58512

so you are interestedin geometry

Sgernesto

took a class about elementary geometry

the book is 'euclidean geometry and beyond'

by robin hartshorne

user58512

I tried to read a book by him.... hehe

user19161

20:00

Best elementary geometry book I know of is by Agricola and Friedrich.

user19161

Not many people know about it.

Sgernesto

thanks

i've seen it in my library but haven't read it

user19161

Covers the classical theorems as well as platonic solids, transformations etc.

user19161

Also covers 2D spherical and hyperbolic geometries.

user19161

Translated from the German.

user19161

20:03

Germans are the best mathematicians. =)

Sgernesto

:)

user19161

The AMS mathematical library series is excellent.

user19161

Makes great upper undergrad courses.

user19161

Also see Hulek's Elementary Algebraic Geometry and Kuhnel's Differential Geometry.

Sgernesto

i know also the collections 'sums' and 'umts' by springer

user19161

20:05

These three books cover the three parts of "geometry": elementary, algebraic and differential.

user58512

I would like to more about what Algebraic Geometry is, I don't have a good idea

Sgernesto

i can't tell you

but i know there's a subject called 'algebraic curves'

that's a prerrequisite

user19161

Interesting thing is all three above are translated from German. =)

Sgernesto

by the way, how many books of mathematics do you think there are?

user58512

wow I have no idea

Sgernesto

20:10

because i've seen collections in my library that have more than 2000 books

i know this because they're numbered

of course those are advanced and specialized books

i have downloaded more books of mathematics than i could possibly read even if i could understand them :D

user58512

how to show zeta has infinitely many zeros in the critical strip?

user19161

0

Q: Which one is a proper example to teach "mass" in the class? (4-8 grades)

Which one is a proper example to teach "mass" in the class? (4-8 grades) Could anyone pls help me? I thought "chalk" but I'm not sure. Thank you so much -Textbook -Blackboard eraser -Chalk -Ruler

homework

user19161

Guys do you understand this question? Hmm...

Ed Pegg

At the University of Illinois Math Library, there are over 100,000 different math books.

4

Orange Harvester

20:26

The Wren Library at Cambridge is supposed to get a copy of every book that has ever been published in UK.

user19161

But many are published in the US. =)

user58512

what if zeta had finitely many zeros in the strip?

user19161

Springer is good, but AMS is catching up fast and furious.

user19161

CUP and OUP books are usually very exotic.

N3buchadnezzar

Hmm

Maple sucks

Jonas Teuwen

20:49

@OrangeHarvester Yes, I use it.

Old John

@JonasTeuwen Hi there

Jonas Teuwen

@OldJohn Hi.

Old John

how are things?

Jonas Teuwen

The president had a presidential party. So to say.

It was called 'Play pool with the president'. And I am the president.

Old John

@JonasTeuwen excellent

Jonas Teuwen

20:52

Well, officially it was named as 'Play pool with PromooD!'

I managed to convince 0,0 people to use emacs.

I guess they were there for the free beer.

Old John

@JonasTeuwen free beer is a serious attraction - emacs not so much :)

Jonas Teuwen

But I had the drinking vouchers...

So first they needed to talk about emacs. Then get voucher.

pourjour

@OldJohn hi!

Ed Gorcenski

Did you stumble over the step where you had to convince them to reinstall a different operating system that they don't know how to use?

Old John

Hi @pourjour Keef harlach?

Jonas Teuwen

20:55

They were already using Linux.

But Vi and things like that.

Old John

@EdGorcenski and emacs runs under many OSes

pourjour

@OldJohn you mean keef halak? : I'm fine thanks and u?

Old John

I used to use emacs under windows - before I saw the light :

user58512

how do I undelete my question?

Old John

@pourjour alhamdu lillah :)

@pourjour how is the maths these days?

pourjour

20:57

@OldJohn not bad, with started the second semester and we still in "complex numbers"

Old John

@pourjour good! - complex numbers are extremely important

pourjour

@OldJohn yeah, I started realizing this fact

Old John

many things are not clear when you only consider real numbers, but become very clear when you look at them from the point of view of complex numbers

Tim

for example?

Old John

convergence of power series for $\frac{1}{1+x^2}$

user58512

21:01

trig identities

pourjour

@OldJohn how is that related to complex numbers?

@user58512 yep

Old John

seen from the reals, there seems to be no reason why its radius of convergence should be 1, but in the complex plane, it has poles at $\pm i$ and it is clear why the radius of convergence is 1.

radius of convergence = distance to nearest pole in the complex plane

Tim

Some quick questions: Is a random measure a stochastic process? Can a random measure be viewed as a family of random variables?

Old John

but when you only look at that function as a function of a real variable, it seems to have no singularities at all

pourjour

@OldJohn we still learning trigonometric forms

Old John

21:05

@pourjour yep - and complex numbers certainly help make trigonometry a more unified subject

Tim

I like unifying

pourjour

@OldJohn I'm using a book titled "Complex numbers from A to z" it's really usefull

Old John

@pourjour not seen that one - but it sounds like it ought to be very useful

Tim

I like useful books too

Old John

@pourjour who is the author?

Tim

21:08

Titu Andreescu, Dorin Andrica

pourjour

@OldJohn titu andreescu and Dorin Andrica

@OldJohn I will send it to you hold a moment

Tim

Is the book for high school?

pourjour

@Tim it covers all things about complex numbers

Tim

@pourjour University level?

number theory level?

pourjour

@Tim at least it covers high school

@OldJohn sent!

Tim

21:11

@pourjour May I ask if you are in high school?

Old John

@pourjour got it - thanks

pourjour

@OldJohn you are welcome

@Tim yesI am

Tim

@pourjour got it - thanks

user58512

mathoverflow.net/questions/13647/…

It says "Using analytic methods .. |F(s)|_r grows exponentially with r" but how do I prove it?

Old John

@pourjour looks very thorough

but it seems to have a "maths olympiad" flavour to it, which I think might not be ideal

pourjour

21:14

@OldJohn I like it because it gives pretty good problems with solution and useful technics

user58512

I think all of Andreescu's books are like that

Old John

@pourjour oh yes - it certainly has lots of problems!

Tim

@user58512 So do you also recommend other books by the author?

user58512

no

Old John

I would use it to to get a good grasp of complex numbers - with the aim of moving onto complex analysis at a later date

user58512

21:16

I didn't recommend that one either

pourjour

@OldJohn enjoy it!:)

Old John

@pourjour I will :)

Tim

:)

user58512

:(

I don't get infinitely many zeros of zeta

Old John

The most interesting book I have read recently was "Visual Complex Analysis" - gives a great insight into things that are not often taught that way

Tim

21:19

Is it rigorous?

user58512

can i undelete my question?

Tim

only moderators can

Old John

@Tim It is not a theorem-proof sort of book - its aim is to give a visual/intuitive understanding of why things behave they way they do in complex analysis - and I think it does that extremely well

Tim

thank! :)

Old John

I thought I knew a lot about complex analysis, but the book certainly taught me a few things

Tim

21:22

What books you knew a lot about complex analysis from

Old John

@Tim Conway (2 volumes) Remmert (2 volumes) Ahlfors ... and several older books

Tim

@OldJohn Thanks. Have you happened to learn about random measures?

Old John

@Tim No - never come across them, sorry

Tim

:)

user19161

Hey @old I answered a few more lhf today. =)

Tim

21:25

Is my question lhf?

Old John

@JacobBlack I did just one lhf today

Tim

=)

Old John

@Tim nope - it isn't

Tim

=)

Look, Jasper becomes Jacob

user19161

@Tim Yes, LOL. And Tim becomes?

user19161

21:28

Tim becomes Gowers, LOL

Tim

Why is Gowers?

LOL

user19161

HAHA, do you know Timothy Gowers?

Tim

Not till you mentioned him

Theorem

@JacobBlack : yes i know him

but i think he doesn't know me hehe

and i am sure

user19161

HAHAHA

Tim

21:30

Is he your idol?

Theorem

i follow his blog . @JacobBlack

user19161

@Theorem I am sure he knows you, since you are Theorem.

Tim

I admire people in functional analysis

Theorem

He should know actually

user58512

I don't understand what's wrong with my proof math.stackexchange.com/questions/298303/…

if you run it for a=1,b=2,p=3 you get 1*2 = 3^2 - 3 = 6

oh its becaus eI added instead of subtract

Argon

21:35

@JacobBlack What day is it?

:)

user19161

@Argon youtube.com/watch?v=kfVsfOSbJY0 Here!

Tim

It is Perfect day

user58512

21:49

I wish people would help me a bit more on my question, its not useful to just repeat whats in the thing I linked asking more details on

Will Jagy

@OldJohn, question on books for harmonic analysis.
http://math.stackexchange.com/questions/298336/reference-for-harmonic-analysis-course

Enjoys Math

How do you get mathjax to display in chat room/

Ed Gorcenski

look on the right, where it says "LaTeX support for chat"

Enjoys Math

22:06

Doesn't say

George V. Williams

@EnjoysMath, meta.math.stackexchange.com/questions/1088/…

Ed Gorcenski

Over above all the starred messages

Enjoys Math

^-^

Jonas Teuwen

23:01

@WillJagy Not passed out yet.

The President was really thirsty.

user19161

Haha I just got the most ridiculous downvote ever.

user19161

I think it is time to retire, LOL.

Jonas Teuwen

LOL.

Old John

@JacobBlack where?

user19161

@OldJohn math.stackexchange.com/questions/298378/… Do they even know there are so many ways to interpret that question?

Old John

23:08

@JacobBlack I am sure they don't - and I think it is a badly-worded question to boot :)

Tim

@JonasTeuwen Hello, President Jonas

Jonas Teuwen

Hello.

Tim

I have many lhf's to pick

:)

user19161

Haha, and I made no typos this time. And there was no comment with a similar answer in it.

user19161

The downvote is NUTS!

Tim

23:10

NUTS

2

draks...

Hey there

user19161

@Tim Oh better not leave any "anger in the chatroom" comments, it is noise. =)

draks...

just a short announcement for number theorists:
I set a bounty for this one
http://math.stackexchange.com/q/269997/19341
The bounty will be granted for the best work out of Greg's answer. Since Raymond's contributions might be very helpful to recall the necessary math, upvoting his answers is highly appreciated...
Good night!

Jonas Teuwen

I hate bounties.

user19161

23:41

Here comes the great @ethan!

Orange Harvester

23:57

Good Morning Everyone.

@JonasTeuwen Good Night. :P

Jonas Teuwen

@OrangeHarvester Good night, Orange :P.

@JacobBlack What did you say? Knife? Back? Are you sure?

Orange Harvester

@JonasTeuwen Have you got any of them? I was lucky when LVK was dishing out some. I have a +100 bounty! :-)

user19161

@JonasTeuwen WTF are you saying?

Jonas Teuwen

@OrangeHarvester I once handed one out?

@JacobBlack I don't know.

Orange Harvester

@JonasTeuwen But your account does not show it. :-/

user19161

23:59

@JonasTeuwen I think Ethan will be a great number theorist one day, so I called him great, nothing wrong bro.

Jonas Teuwen

@JacobBlack That might be true, I will always remember the backstabbing.

user19161

@JonasTeuwen Backstabbing? What are you talking about? Explain!

Transcript for

$Mathematics$ Mathematics